Need a little help on troubleshooting

ok here goes,
I have a 92 cherokee with a 4.0 5spd and almost 185k miles on it, the problem i've been having is that it won't start when i turn over until i push the gas pedal to the floor then it sputters to life, at first it'll sound like a motorcycle at around 1000-1500 with gas pedal to the floor then it'll eventually run smooth, it also very easy to stall out on accelleration. when I romp on the gas pedal it'll hesitate then lurch violently then run normally, when i slowly push the pedal it goes a little smoother but i also have to rev the rpms to over 1500 then let of the clutch to accelerate from a stop without stalling.
Now I'm guessing it could be one of few things: bad O2 sensor, bad Fuel pump/clogged fuel pump, bad Throttle Position Sensor, or bad Engine control computer.
is there any other possibilities? what is the most likely cause? I want to get this fixed without buying the unecessory parts.
sorry I'm used to fixing old carburated generic vehicles. any help is greatly appreciated.

Need Troubleshooting help.

ok here goes,
I have a 92 cherokee with a 4.0 5spd and almost 185k miles on it, the problem i've been having is that it won't start when i turn over until i push the gas pedal to the floor then it sputters to life, at first it'll sound like a motorcycle at around 1000-1500 with gas pedal to the floor then it'll eventually run smooth, it also very easy to stall out on accelleration. when I romp on the gas pedal it'll hesitate then lurch violently then run normally, when i slowly push the pedal it goes a little smoother but i also have to rev the rpms to over 1500 then let of the clutch to accelerate from a stop without stalling.
Now I'm guessing it could be one of few things: bad O2 sensor, bad Fuel pump/clogged fuel pump, bad Throttle Position Sensor, or bad Engine control computer.
is there any other possibilities? what is the most likely cause? I want to get this fixed without buying the unecessory parts.
sorry I'm used to fixing old carburated generic vehicles. any help is greatly appreciated.
sorry should have posted to here the first time lol.

Re: Need Troubleshooting help.

http://www.jedi.com/obiwan/jeep/dtc.html Does a pretty good job of explaining pulling the trouble codes from your computer.
Sounds like you have some serious cross fire in your ignition wires or the inside of your distributor cap is kind of burnt and green and/or maybe full of moisture.
Sounds like your discribing mine, after a trip through a too deep puddle.

It cartainly sounds like a fuel delivery problem and if you still have the original factory fuel pump, it's probably on its last legs.
Check the fuel pressure at the injector rail. It should be ~30psi with the vacuum to the fuel pressure regulator connected, and ~39psi if it isn't. If it isn't within spec, change the fuel filter. If that doesn't cure it (unlikely), you need a new pump.

Possibly an ignition issue... how old are the plugs/wires/cap-button/coil?

Also as you point out it could be a fuel delivery/mixing issue: check fuel pressure, swap air & fuel filters, clean throttle body and injectors.

A broken hose between the MAP sensor and the throttle body makes for a poor running jeep (this might be a RENIX era issue though, unclear if the HO has one) but I don't think this would be an intermittent thing.

ok the spark plugs, wires and distributer cap is all new (7 months), and yes the fuel filter and pump is still factory, so hopefully that kinda narrows down the problems,
oh yeah it also idles at a higher rpm than normal now, a little over 1000 instead of 750-800

Ok, I've experienced similar problems with my '91. First off, while it may be a good idea to change your fuel filter, it sounds like you are running too rich. By putting the throttle to the floor while cranking you activate "clear flood mode" stopping fuel flow. My first guess would be the TPS is not seeing the throttle being fully closed and thus you are getting too much fuel at start-up and at part throttle leading to poor starts and part throttle stumbling. I'm no expert but I have toasted 4 TPS's in the past 6 years so that's where I would start. I should note that the last TPS I instaled was slightly different than the others and has not given me an problems in several years of use. All were from the dealer so I guess this must be an updated part.

Tony

Have you put a vacuum gauge on it to see if it's got any symptoms? On the FI Jeeps, some fuel related problems, such as a bad injector, will not show on a vacuum gauge, whereas ignition and internal engine problems will. That can be a good way to narrow it down.

Well this is kinda funny,
I did measure the fuel pressure and it was fine the fuel pump still worked perfectly and disconnected the fuel lines connecting to the rail just in case there is anything clogging it like dirt or peices of filter element (it has happened to my freind before) but i found nothing, so i put it all back together again, well now it runs fine my guess is that its a fuel line "burp"-
when you stall out and flood a fuel injection system there is excess fuel in the system and everytime you start or accelerate it dumps more fuel on top of that thus its starving for air because its trying burn the excess fuel and since its a sealed system unlike carburators it'll take hours sometimes even days to clear up unlike carbs which usually only takes a few minutes.

So alls I'm going to do is replace my fuel filter since its been on quite awhile quite possibly still factory, definately not going to be a Fram brand either my friends Wrangler had one installed and its fuel lines and rails got clogged due to the filter element and the cardboard disintigrating and the peices traveled throughout the system making a mess and it was only like 8 months old. I also feel the same about their oil filters.